KR20010080943A - All-weather fluorescent lamp with a protective assembly - Google Patents

Abstract

The fluorescent lamp 10 includes a protective tube 16 and a glass tube 12. In the vicinity of the end caps are provided a plurality of vent holes 30 of a particular quantity and size.

Description

ALL-WEATHER FLUORESCENT LAMP WITH A PROTECTIVE ASSEMBLY}

In most instances, prior art fluorescent lamp protectors have a special molded end fitting that fits over the terminal cap of the lamp and secures the protective sleeve in place on the lamp. In some cases, the end fitting is intentionally designed to be detached from the lamp so that the guard can be reused when the lamp is replaced at the end of its life. Detachable protective devices do not prevent the glass fragments and the fluorescent powder from splashing completely in the event of a lamp failure. Regardless of whether the end fittings are permanently attached to or detachable from the lamps, they should be designed to be relatively expensive and usually in the form of special lamps to ensure proper fitting.

The lamps of the '637 patent (above) of the applicant have excellent protection against breakage of the lamp, and if the lamp breaks, the protector surrounds to ensure that the glass fragments and the fluorescent powder are splashed. In that regard, the guard tube on the lamp tube is firmly coupled to the terminal cap of the lamp by a collar that is firmly attached while mechanically engaging the guard tube and the terminal cap. The lamp of the applicant's' 637 patent uses a simple tubular element and commercially available adhesives, resulting in low production costs.

The above-mentioned Applicant's' 998 patent also relates to a protective fluorescent lamp configured to operate at low temperature conditions, such as in a supermarket freezer or refrigerator or cold weather. It uses standard “room temperature” (70 ° F., 21 ° C.) fluorescent lamps and has a protective tube fixed radially spaced from the glass tube of the lamp by a compressible foam spacer ring at each end. The gap between the glass tube and the protective tube of the lamp provides the air gap between the lamp tube and the protective tube. The air trapped in the air gap prevents heat transfer from the lamp to the surrounding air outside the protective tube and forms an insulating layer that circulates the air for convective distribution of heat along the length of the lamp. The retention of heat in the air gap prevents the lamp from cooling and maintains brightness at or near the lamp brightness at room temperature. Sheaths absorb shocks to minimize the possibility of lamp breakage. If the lamp breaks, an enclosure consisting of a sheath, collar and terminal cap has a heat fit color which not only mechanically engages the flange and sheath but also is bonded to the flange and sheath of the lamp terminal cap by an adhesive. ), The lamp fragment and the phosphor powder are confined.

The foam spacer ring serves several functions. First, it is a spacer to the protective tube from the glass tube of the lamp in that it forms an air gap uniformly with respect to the lamp tube at each end. Since the sheath is generally rigid, the uniformity of the air gap along the length of the lamp is ensured by forming a gap at each end. Second, the foam spacer ring provides thermal insulation at the end of the air gap and prevents cold spots from forming at the end of the sheath. Third, the foam spacer ring forms a shock absorbing cushion between the protective tube and the lamp tube, which reduces the likelihood of the lamp breaking due to an impact near the tube, in particular near the end. The spacer ring is bonded to the lamp tube by an adhesive, so that when the protector is installed over the lamp, it not only slides over the lamp but also remains in place until the end of the lamp's life. The fit between the spacer ring and the guard tube is a "snug fit" to allow the guard to slide over the lamp with the spacer ring already in place without forcing the lamp tube while enhancing the insulation. Since the ring is a compressible foam, it can be slightly compressed so that the sheath cannot slip over the ramp.

Applicant's '998 and' 637 patents are used herein for any purpose.

Lamps equipped with protective devices according to the Applicant's' 998 patent, which are readily available on the market, are intended to be extremely low temperature, as intended, in the temperature range from freezing point (32 ° F, 0 ° C) to -34 ° C (-30 ° F). Works great. At higher temperatures in the range and at temperatures above freezing, these lamps tend to overheat, shortening their lifetime and decreasing the brightness as the ends of the protective cover discolor over time. In certain circumstances, such as refrigerated showcases for products that are refrigerated at slightly higher temperatures, such as produce, dairy products, salad dressings of any kind, and other products, the protection lamps according to the applicant's' 998 patent do not function properly. can not do it. On the other hand, the protection of room temperature lamps as disclosed in the applicant's' 637 patent is also unsatisfactory because the brightness is reduced at temperatures below about 10 ° C. (50 ° F.).

When the fluorescent lamp is broken, debris in the glass tube, mercury and powder from the fluorescent coating inside the tube are scattered around. Showcases where food is being processed or stored, especially in shops with food inventory and in supermarkets where customers handle food in the vicinity of the showcase lamps, in a manner that minimizes the chance of the showcase lamps breaking. It is, and is desirable, for government regulation to protect showcase lamps and to eliminate the possibility of glass fragments, mercury and fluorescent powder splashing out and contaminating food, even if broken. For this purpose fluorescent lamps with protective equipment are already known and widely used. Examples of such lamps are U.S. Pat. , 1998). The three patents behind them are owned by the assignee of the present invention.

Storefronts for frozen foods will need to minimize lamp breakage and the possibility of glass and powder splashing, as well as maintaining optimal lamp brightness in low temperature environments. Fluorescent lamps designed to operate at room temperature (about 70 ° F) have less brightness at ambient temperatures below room temperature. Thus, there have been a myriad of proposals for fluorescent lamps suitable for low temperature operation, as described in US Pat. No. 2,135,696 (Baumhauser et al., 1938); 2,363,109 (Keiffer, 1944); 2,581,959 (Koehler, 1952); 3,358,167 to Shanks, 1967; 3,453,470 (Hammer, 1969); 3,602,759 (Evans, 1971); 3,720,826 (Gilmore et al., 1973); And 4,916,352 (Haim et al., 1990).

1 is a side cross-sectional view of one end as an embodiment of a protective device fitted over a conventional fluorescent lamp, and since both ends have the same structure, the other end is also symmetrical in shape.

2 is a side elevation view of an embodiment of a protection lamp embodying the present invention, with the center portion omitted.

It is an object of the present invention to provide a protective lamp assembly which can be used over a wider temperature range than the lamps of the applicant's '637 patent or' 998 patent. In particular, it is an object of the present invention to provide a protection lamp assembly for use in a temperature range from about 10 ° C. (50 ° F.) to about −34 ° C. (-30 ° F.). This range is, for example, the range in which the same protective lamp assembly can be used in both the refrigerator compartment and the freezer compartment.

The above and other objects are, according to the present invention, by improving the protective assembly for a standard fluorescent lamp in the form of an elongated glass tube and a metal terminal cap at each end of the glass tube, each having a flange portion near the glass tube. Is achieved. The assembly is preformed from semi-rigid, semi-rigid, unbreakable transparent or translucent polymer material stabilized against ultraviolet light and is generally uniform from the outer face of the glass tube so that the inner face forms an air space for insulation of the lamp. A protective tube spaced apart and received over the glass tube. The guard tube extends generally together with the entire diameter portion of the glass tube in the longitudinal direction of the lamp and is fixed to the flange of the lamp so that the guard tube remains fixed to the end cap in the event of a lamp failure.

It is an improvement that a large number of vent holes are provided in the part of the protection tube near the end cap. The vent holes are large enough to prevent glass fragments from leaking out of the broken lamp tube. The number of vent holes is such that the air gap between the glass tube and the protective tube of the lamp is maintained without a substantial decrease in brightness and without substantial discoloration of the protective tube in the ambient temperature range of about 10 ° C. (50 ° F.) to -34 ° C. (-30 ° F.). It's enough to work.

Two important features of the improvement according to the invention are: (1) from a protective tube / terminal cap structure in which solid materials such as broken glass fragments and fluorescent particles are not damaged even when the vent holes are small enough to break the glass tube of the lamp. (2) the holes are arranged in such a number as to allow only limited ventilation in the air space between the glass tube and the protective tube of the lamp. It is not easy to quantify the degree of ventilation and we have not tried to quantify it, but if the air volume is too high, the lamp will operate at too low a temperature, and the brightness will decrease significantly. If the air volume is too low, the lamp will operate at too high a temperature. In particular, the temperature of the lamp will cause discoloration near the highest end. The appropriate amount of ventilation can be determined by experiments performed in the examples described later.

In particular, if the diameter of the vent hole is about 1.27 mm (0.050 inch), it is small enough to prevent the solid material from coming out of the seal formed by the protective tube and the end terminal (as opposed to the gas) in the event of a broken glass tube of the lamp. It is known. The holes at each end of the sheath should be evenly distributed in the circumferential direction of the sheath. Good results are obtained if all vent holes are located within about 3 inches of each end of the sheath. For example, the lamp life and lamp brightness of a protection lamp operated at various ambient temperatures between 10 ° C (50 ° F) and -34 ° C (-30 ° F) are maintained close to that of a standard (unprotected) lamp operating at room temperature. In this experiment, 72 vent holes with a diameter of 1.27 mm (0.050 inch) are arranged in three rows of 24 at equal intervals in the circumferential direction at each end of the protective tube, and 22 mm (7/8 inch) between the rows. Apart

To help a deeper understanding of the present invention, exemplary embodiments will now be described with reference to the accompanying drawings.

Referring to Fig. 1, reference numeral 10 denotes a conventional room temperature fluorescent lamp which is readily available on the market, which is a cup-shaped metal terminal cap with a slight taper at each end and an outer flange 14a at each end. It is a form provided with the elongate glass tube 12 closed by (14). The lamp base may be in the form of a conventional two pin, one pin or recessed dual contact (as shown). The guard is preformed from a semisolid, unbreakable transparent polymer material which is received over the glass tube and extends approximately the same area in the longitudinal direction of the glass tube with a clearance "C" between the outer surface of the glass tube and the inner surface of the protective tube. It consists of 16 pieces. A spacer ring 18 is located near each end of the glass tube, whereby a spacer or gap "C" is formed and maintained between the lamp tube and the protective tube. Each spacer ring is adhesively bonded to the glass tube by an adhesive layer 18a, formed of a semi-solid polymer foam strip material that is resistant to heat and ultraviolet rays, the cross section of which has a generally uniform rectangular cross section and the outer surface of the ring is a protective tube It is the shape of a band having a thickness that forms a snug fit with the inner surface of the to allow the protective tube to slide longitudinally with respect to the lamp. The collar 20 preformed from the heat shrinkable polymer material is received overlapping over the portion of the protective sleeve at each end and over the flange portion of the adjacent cap. The collar 20 is heat-shrunk and sealed to the protective tube 16 and the cap flange portion 14a. An adhesive layer 22 is interposed between each collar 20 and an end of the corresponding protective tube 16 and an adhesive layer 24 between each collar 20 and the corresponding cap flange portion 14a. ) Is intervened. There is no adhesive between the glass tube of the lamp and the collar 20.

In certain embodiments of the present invention applied to fluorescent tubes of 38.1 mm (1.50 inch) diameter, the protective tube 16 may be formed of an extruded material of polycarbonate resin that is very stable against ultraviolet radiation over the entire diameter portion of the lamp tube (the tapered portion at each end). Not to the top) is cut to length to extend in the longitudinal direction. The sheath may be transparent or translucent or in any case have a color. A commercially available transparent polycarbonate tube, commercially available, is Part No. 58UV from Thermoplastic Processors, Sterling, New Jersey, made from a resin supplied by Mobay (Res. No. 3207-1112M50). The protective tube has a wall thickness of 1.59 mm (0.0625 inch) and an inner diameter of 49.2 mm (1-13 / 16 inch). The gap or gap between the outside of the glass tube and the inside of the protective tube, in the radial direction, is 2.38 mm (3/32 inch). The gap is preferable in that a thermal insulation layer of air is formed between the glass tube and the protective tube of the lamp to maintain a desirable temperature difference between the lamp tube and the environment outside the protective tube. The gap also allows for a flow of vent air to maintain a desired temperature gradient along the longitudinal direction of the lamp.

The spacer ring 18 is a strip of silicone rubber foam having a generally uniform cross section, rectangular, having a width of 12.7 mm (1/2 inch) and a thickness of 6.35 mm (1/4 inch). The foam has a compression strain of about 41.4 kPa (6 psi) to about 95.6 kPa (14 psi) at 25% compression (ASTM D1056). The foam has an acrylic adhesive coating on one side and a release liner on the adhesive. To form a ring, a piece of foam tape is cut from the feed roll to the length needed to wrap around the lamp tube and form a snug butt joint where the two ends meet. The tape is attached to the lamp so that the edge closer to the lamp terminal cap approximately coincides with the end of the sheath.

Collar 20 is NJ. Tube product which is commercially available. This part was cut to a length of 38.1 mm (1-1 / 2 inch) from E.H.Canis & Son's trade name "Astramelt FP301" in Metuchen. About 19 mm (3/4 inch) of the collar overlaps the sheath. The adhesive is GE PSA and provides additional mechanical preservation over what is provided by shrinking the collar and provides a moisture barrier and sealing seal between the lamp and the protector.

If the protective lamp is broken, the protective device retains the cap to prevent dispersion of glass fragments and phosphor powder. Since the sheath is entirely transparent, it is believed that the guard does not reduce the transmission of light.

To ensure proper operation of the protection lamp at a temperature of about 10 ° C. (50 ° F.) without reducing the life and discoloring the protection tube 16 near the end where the lamp is hottest, each end of the protection tube 16 In the vent hole 30 is formed. In this embodiment, all vent holes are equally 1.27 mm (0.050 inch) in diameter. The size of the pores is determined to be small enough to prevent glass debris and phosphor particles from escaping from the glass tube when the glass tube of the lamp breaks and to prevent mercury from leaking out from inside the tube. The vent holes are evenly distributed on the circumference of the protective tube, thus eliminating the possibility of uneven ventilation depending on the direction of the protective lamp. The number of holes required to keep the lamp's operating temperature low enough to avoid problems with ambient temperatures on the order of 10 ° C. (50 ° F.) is about 72 at each end of the sheath. Proper placement of the holes is 22.2 mm (7/8 inch) away from the end and the row nearest the end of the sheath and the three rows in the circumferential direction are spaced about 22.2 mm (7/8 inch) apart.

The specific configuration described above is intended as a guide. It is clear that different hole patterns, different number of holes, and holes slightly larger or smaller than 1.27 mm (0.050 inch) can produce good results. Arrangement of holes of any size to trap glass fragments, phosphor particles, and mercury from broken lamps and positions and quantities in sheaths that provide ventilation to prevent the lamp from overheating to temperatures up to 50 ° F (10 ° C). Suitable. Vent holes have been shown to essentially not change the protection lamp's superior performance at temperatures as low as -34 ° C (-30 ° F).

One form of confinement of material scattered by a lamp with a protective device described above is that the initial pressure in the protective device drops considerably below atmospheric pressure since the low vacuum volume in the lamp is added to the volume of the air gap when the lamp is broken. Will. Thus, air flows through the vent holes into the limited volume provided by the terminal caps and sheaths. The inflow of air prevents material in the restricted volume from escaping through the vent holes. Even if the pressure in the limited volume soon reaches atmospheric pressure after the lamp is broken, the presence of the vent holes does not change the effectiveness of the protective device which prevents the elements of the lamp from escaping due to the inflow of air through the vent holes.

Claims (9)

A fluorescent lamp with a protective device, The lamp has a metal terminal cap having an elongated glass tube and a flange portion adjacent to the glass tube at each end of the glass tube, The protective device is preformed from semi-solid, unbreakable transparent or translucent polymer material stabilized against ultraviolet light, received over the glass tube, the end of which is joined to the flange portion of the terminal cap, the inner surface of which is insulated from the lamp. A protective tube extending substantially uniformly from the outer surface of the glass tube to form an air space for the lamp and extending generally together with the glass tube in the longitudinal direction of the lamp, The part of the protection tube near the terminal cap of the lamp has a plurality of vent holes, and the vent holes are sized so that the wavefront of the glass tube cannot pass through the holes if the lamp is broken. With a protective device characterized by a sufficient number to allow the lamp to operate without substantial discoloration and without a substantial decrease in brightness at ambient temperatures ranging from about 10 ° C. (50 ° F.) to about −34 ° C. (-30 ° F.). Fluorescent lamps. The method of claim 1, Each vent hole has a diameter of about 1.27 mm (0.050 inch). The method of claim 1, The vent hole is substantially evenly distributed around the circumference of the protective tube. The method of claim 1, Each of said vent holes has a diameter of about 1.27 mm (0.050 inch) and said vent holes are substantially evenly distributed around the perimeter of said sheath. The method of claim 4, wherein The vent holes are arranged in a row in the circumferential direction and the vent holes in each row are substantially equally spaced apart from each other. The method of claim 4, wherein And said vent hole at each end of said sheath is located within about 76 mm (3 inches) of said end of said sheath. The method of claim 4, wherein And about 72 vent holes at each end of said sheath. The method of claim 1, Each of the vent holes has a diameter of about 1.27 mm (0.050 inch) and the vent holes at each end of the sheath are arranged in three rows in the circumferential direction, the rows being generally equally spaced apart from each other. A fluorescent lamp having about 24 vent holes equally spaced from each other. The method of claim 8, The column closest to the near end of the sheath is about 22.2 mm (7/8 inch) away from the near end and the rows are spaced about 22.2 mm (7/8 inch) apart from each other. lamp.